Thread

1. Re: PITR, checkpoint, and local relations

   Vadim Mikheev <vmikheev@sectorbase.com> — 2002-08-02T23:50:31Z

   > So I think what will work then is pg_copy (hot backup) would:
   > 1) Issue an ALTER SYSTEM BEGIN BACKUP command which turns on 
   > atomic write,
   > checkpoints the database and disables further checkpoints (so 
   > wal files
   > won't be reused) until the backup is complete.
   > 2) Change ALTER SYSTEM BACKUP DATABASE TO <directory> read 
   > the database
   > directory to find which files it should backup rather than 
   > pg_class and for
   > each file just use system(cp...) to copy it to the backup directory.
   
   Did you consider saving backup on the client host (ie from where
   pg_copy started)?
   
   > 3) ALTER SYSTEM FINISH BACKUP does at it does now and backs 
   > up the pg_xlog
   > directory and renables database checkpointing.
   
   Well, wouldn't be single command ALTER SYSTEM BACKUP enough?
   What's the point to have 3 commands?
   
   (If all of this is already discussed then sorry - I'm not going
   to start new discussion).
   
   Vadim
   
   

2. Re: PITR, checkpoint, and local relations

   Richard Tucker <richt@multera.com> — 2002-08-07T15:01:59Z

   
   > -----Original Message-----
   > From: Mikheev, Vadim [mailto:vmikheev@SECTORBASE.COM]
   > Sent: Friday, August 02, 2002 7:51 PM
   > To: 'richt@multera.com'; J. R. Nield
   > Cc: Tom Lane; Bruce Momjian; PostgreSQL Hacker
   > Subject: RE: [HACKERS] PITR, checkpoint, and local relations
   >
   >
   > > So I think what will work then is pg_copy (hot backup) would:
   > > 1) Issue an ALTER SYSTEM BEGIN BACKUP command which turns on
   > > atomic write,
   > > checkpoints the database and disables further checkpoints (so
   > > wal files
   > > won't be reused) until the backup is complete.
   > > 2) Change ALTER SYSTEM BACKUP DATABASE TO <directory> read
   > > the database
   > > directory to find which files it should backup rather than
   > > pg_class and for
   > > each file just use system(cp...) to copy it to the backup directory.
   >
   > Did you consider saving backup on the client host (ie from where
   > pg_copy started)?
   No, pg_copy just uses the libpq interface.
   >
   > > 3) ALTER SYSTEM FINISH BACKUP does at it does now and backs
   > > up the pg_xlog
   > > directory and renables database checkpointing.
   >
   I think now it could be just one command.  My implementation was reading
   pg_class to find the tables and indexes that needed backing up.  Now reading
   pg_database would be sufficient to find the directories containing files
   that needed to be archived, so it could all be done in one command.
   
   > Well, wouldn't be single command ALTER SYSTEM BACKUP enough?
   > What's the point to have 3 commands?
   >
   > (If all of this is already discussed then sorry - I'm not going
   > to start new discussion).
   >
   > Vadim
   >